In certain curing applications, such as semiconductor processing of films, flat panel display fabrication, and wide-web applications, fairly large (e.g., 10 in long) elongated UV emitting lamps have been employed to irradiate the surface of a large-area substrate (e.g., a semiconductor wafer). The resulting irradiance pattern over an irradiated substrate is generally non-uniform. Related art irradiating optical systems have employed complicated optical designs to correct non-uniform irradiance. This has resulted low efficiency (or entendue) of the radiating optical system as additional optical components are added to the system to improve the non-uniform irradiance.